A steering lock device for use with a steering shaft includes a lock bar, a camshaft, and a counterweight. The lock bar is moved between an engagement position where the lock bar is engaged with the steering shaft and a non-engagement position where the lock bar is disengaged from the steering shaft. The camshaft is rotated in response to a locking operation and an unlocking operation. The camshaft includes a lock actuation cam that moves the lock bar to the engagement position in a locking direction, and rotation of the steering shaft is prohibited when the lock bar is engaged with the steering shaft. The counterweight is arranged on the camshaft to adjust rotational balance of the camshaft.